Science and Technology 11 Mrs. N. Gill Forensic Science Science and Technology 11 Mrs. N. Gill

Topics to be covered: Introduction to the terminology of Forensics Processing a crime scene and physical evidence Fingerprints Chromatography Blood and fibres Document analysis

Introduction to the terminology of Forensic Science Forensic is the application of science and technology to the law and solution of crime. Science and technology are used to gather information at the scene of a crime. The first forensic scientist is the fictional character Sherlock Holmes. He used fingerprinting, document examination and blood analysis to solve crimes. Modern forensic science is more complex, as it uses behavioural science as well, which seeks to understand why people behave as they do.

Purpose Discovering, collecting and analyzing evidence Prove truth or false of a law Chemistry is used to analyze substances found at crime scenes. Physics helps to explain about motion of objects E.g. What happens when a gun is fired. Biology is used to analyze evidence left by people to determine how a person died. Forensic science uses many technologies to gather evidence at the scene of a crime and to analyze that evidence in the lab:

Still and video photography is used to record crime scenes for further analysis and courtroom use. Special lights are used to discover biological evidence such as blood, even when it is not visible to the investigators. In the lab, different types of microscopes are used to examine small pieces of evidence. Specialized equipment is used to analyze unknown substances. Computer databases are used to compare fingerprints taken from a crime scene to millions on the file

The Forensic Team The first person to arrive at a crime scene is a uniformed police officer. He will secure the scene to preserve evidence and decide who else is required. An ambulance may be needed to treat the injured; detectives with special skills may be called

Departments of Crime labs are as follows: 1. evidence collection units (CSI – crime scene investigators): Specially trained personnel to collect and preserve physical evidence. They use a variety of tools and techniques to find and gather evidence e.g. Taking photographs and making sketches. CONTENTS OF THE CSI TOOL KIT: Special gloves – so they don’t contaminate the evidence. Eye protection – when using special chemicals

Still and video cameras – to record the crime scene Chalk – to mark the position of objects by outlining them before they are removed. Bags, envelopes and tubes – to take the evidence to labs for analysis. Special tapes and powders – for recovering fingerprints. Lights – to enhance viewing the scene and for discovering bodily fluids. Magnifying glasses – for locating evidence such as fibres. Rulers and tape measures – for recording dimensions and distances. Crime scene tape – to mark off and protect the crime scene.

3. forensic pathologist (medical examiners and coroners): 2. physical science: use of chemistry, physics and geology techniques to identify and compare crime scene evidence. 3. forensic pathologist (medical examiners and coroners): they are physicians who specialize in forensics and are responsible for investigating unnatural, unexplained or violent deaths. Medical examiners work begins at the crime scene and continues in the lab. They also perform autopsies to gather evidence. Once the case reaches the courtroom they testify as expert witnesses.

6. Fingerprint unit: process and examine evidence for fingerprints. 4. Crime lab Technicians: they analyze the evidence found at the crime scene. A) toxicology unit – body fluids and organs examined to determine the presence or absence of drugs and poisons. B) biology unit – biologists and biochemists identify DNA profiles from body fluids. 5. Photography unit: examine and record physical evidence, prepare photographic exhibits for court. 6. Fingerprint unit: process and examine evidence for fingerprints. 7. Firearms unit: examines firearms and ammunition of all types as well as examine garments for firearms residue.

8. Document examination unit: handwriting and print materials are studied, analysis of paper and ink. 9. Forensic anthropology unit: Identification and examination of skeletons. 10. Entomology unit: study of insects helps in aid in time of death. 11. Odontology: used if body is left unrecognizable (evidence that may be derived from teeth), bite mark analysis 12. Forensic engineering: failure analysis (investigation of materials, products, structures or components that fail or do not operate or function as intended), accident reconstruction, causes and origins of fires.

Goals of criminal investigators: Determine if a crime has been committed. Obtain information and evidence to identify person(s) responsible for crime. Find suspect. Present the case in court.

Death Classification: Natural – caused by naturally occurring disease process. Homicide – act of killing another human being. Suicide – wilful destruction of one’s self interest or life. Accident – an unexpected death. Undetermined – not knowing what caused the death.

Several Stages Rigor mortis Livor mortis Algor mortis Muscle relax followed by rigidity 24-36 hrs. Livor mortis Blood pools in parts closest to the ground (depends on the position its in at...) Dark blue or purple appearance. No discoloration in constricted areas (clothing or object; can tell if a person was moved) Begins immediately and lasts for 12 hours Algor mortis Body cooling to surrounding temperature Normal temp -37 degrees rectal 1.5 degree Celsius per hour. Dependant on clothing, body size and weather condition.